♠️ M77
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Stand Switch would be #1 and then replacing the Clutch Switch (would not bypass it) as if the ECU thinks you’re holding the clutch all the time , it might get funny as I can’t fully confirm how much Hyosung has programmed their ECU to depend on user actions (rather than bypasses) If you said GV125 carb model = it would not matter as Hyosung didn’t always include stand switches or clutch switches , they didn’t matter too much. Also in my experience one of my bikes was in NEUTRAL (according to the dash) and i pushed start , it rolled and fell down , so false neutrals are rare and can happen , hence “hold clutch in” before starting is enforced on these 2018+ new models of bikes coming out now. Neutral Switch , complicated as it is also a gear counter, so i would not mess with it. ECU may read what gear you’re in to optimize ignition behavior etc
I got her bumpstarted. Does this mean that the safety switches haven’t failed?
How did you bump start it ?
And for parts = working on it. Look out for bits being displayed on the shop as i now have extra supply chain links to get stuff without depending on South Korea all the time. keeps us on the road sooner.
I’ll send an email for a quote, the reg rec you sent me earlier, it will work fine with my bike right? Just to confirm.
I personally take the extra days to make the connectors and build the mini harness to fit your bike , i can never encourage wire chops to be fair (this bike just went up in smoke now, click here…..) , part of the cost is labour making those harness pig tails for the reg-rec and buying the special big connectors as you found out, they are quite specific size , and i have to be sure the regulator is also good after its stripped from another bike but it’s best to read the whole link i gave you earlier so you can understand what this kit is (what’s inside the box etc) (& extra time needed)
I do the same thing for various models like these down here
Upgrade Regulator Rectifier & Stator Generator – GV650 GT650 Hyosung {Carby & EFi up to 2013}
Upgrade Regulator Rectifier & Stator Magneto – Hyosung GV250 GT250 [EFi DELPHi 2011-2015]
And no worries about the uploader, if it works for others it’s fine. I’m okay with sending links.
Thank you and sorry again you have been a great help spotting bugs! – Technology is never perfect! – I will keep fighting, less hoops for you the better 🙂
Stand Switch would be #1 and then replacing the Clutch Switch (would not bypass it) as if the ECU thinks you’re holding the clutch all the time , it might get funny as I can’t fully confirm how much Hyosung has programmed their ECU to depend on user actions (rather than bypasses)
If you said GV125 carb model = it would not matter as Hyosung didn’t always include stand switches or clutch switches , they didn’t matter too much.Also in my experience one of my bikes was in NEUTRAL (according to the dash) and i pushed start , it rolled and fell down , so false neutrals are rare and can happen , hence “hold clutch in” before starting is enforced on these 2018+ new models of bikes coming out now.
Neutral Switch , complicated as it is also a gear counter, so i would not mess with it. ECU may read what gear you’re in to optimize ignition behavior etc
Batteries and regulators are known to do 100% just that. Fry everything connected to the harness.
Poor bike was not expecting a regulator or battery to kill it. Granted Knockoff regulators (aliexpress ones) or Stock OEM regulators are usually the #1 or #2 i frequently advise people to move up to the Shingden Units (japanese) like what you see on the store but a volt meter attached to the bike can warn the rider while riding that charging system is exceeding 15V limit that Hyosung wants.
Replace the dash its fried. + harness (MAKE SURE the harness & dash match! – If you put a 2012 dash to a 2007 harness, it will go in smoke instantly!)
+ CDI + Reg Rec + StatorIt will be good to go again!
I suspect that you could benefit to replace the HT caps (burst resistors) , use NGK ones , get new OEM coils – We now have sparks!
Things like Lights + Indicators + Relays can be replace bit by bit if there is any budget constraints.
OEM part is infamous but it works until it doesn’t , so no way to tell you how long it lasts , some pop within weeks/days of use and some carry on for years of light-usage but the complaints generally outweigh their benefits , ask the Australians in their bike groups , as such a hot climate down there is making sure its the #1 thing they upgrade before tyres!
I fixed the image uploader but , if you reply one more time and you can’t see it, then it is on me to really force it & reset everyone, incase their devices/browsers saved copies of the old Reply Box. Again , sorry about this!
Clutch Switch , Neutral Sensor , RO Sensor (Roll Over Sensor) , Magneto Pulse Trigger (part of the stator unit)
(mini)baby 6-sided sockets with a swivel works best , 12-sided sockets or spanners are not good. Spray a little bit of penetrant fluid on the bolts and leave to soak overnight, incase there is some kind of rust that was heat fused (joining the bolt and throttle body down) . Also 6-sided O-spanners work best , forget C-shape spanners as they always slip out.
TPS , here is some links that apply to the 250cc too
[Tutorial] How to replace Gt650r throttle position sensor (TPS)
Your TPS is held down by 1 bolt , but some models have TPS held down by 2 bolts, principle is the same. – Usually it is less frustrating to get a new one than trying to fix an old one , incase the rotating contacts inside the old TPS have broken down.
13.5v is the lowest acceptable limit , but caution to upgrade the regulator in the future. Don’t buy knock off aliexpress ones please, they WILL fry the bike!
Though , you can still get yourself another OEM one at your local dealer , if you want to keep it original , personally i use Shingden Japan regs (what you see on the shop) , then again , Shingden gets a LOT of fakes online too but that’s a whole other conversation as I am digressing sorry.
Bike seems OK from what you said, so go have fun 🙂
Thanks for confirming. I didn’t get the parts on this site because I saw UK shipping. I used HyosungWholesale. Do you ship internationally? And would you have this specific regulator rectifier 32800HN9121?
Yes totally! – but we never sell OEM regulators (can’t trust them personally) as they have caused issues since 2001.
We do Shingden kits like these:
REAL MOSFET Upgrade Regulator Rectifier (Reg Rec) – GV125-S Bobber (GV125S EFi Aquila)
Just send an email with your address for shipping quotes
PS. Upload an image of your regulator (the GD one that’s fitted to your bike) right here and we can see if the image uploader works. As i spent a few hours fixing bugs and adding some extra programming to force the button to appear.
Another member has confirmed a bug, so I will fix it and update accordingly, sorry about this!
You have the Delphi V2 harness , (2016+) you need the OEM regulator that uses part number 32800HN9121 – Which is GD250, GV700
Hyosung used GD & ST regulator because they changed the stator unit completely (it is green stator) , older EFi models had black stators with smaller plugs.
Henceforth your GD regulator did fit. I would get the OEM one as it will probably outlive any china-clone (which don’t exist) , china just makes really knockoff ones for older models , they are quite wild (hit & miss in terms of success)
It is probably why I only do true-mosfet Shingden ones like you saw on the shop, fit once and forget about it for years & years (unless your electrics / stator / battery blow it!)
thank you very much for the “bug” in regards to the add-media button , I will fix it!
Just used a test account , it seems to be working fine on my end ?
Do you see this button?
(it is above the white Reply Box)
If yes , then:
Step 1 – Click Add Media Again below:
Then step 2 , click the tab that says “Upload”
Final Step, click “Select Files / Find Files” (it may be a different word depending on PC,Apple, Android etc.)
Then find your pictures (Phone = Gallery / PC = where ever you stored them)
Sorry for any frustration caused , I am actively looking for ways to make image uploads more seemless so there is less hoops to jump through .
If there is bugs (ie. you physically can’t see a specific button eg. “Select Files” or “Add Media” or “Upload ” tab
Take a picture on your phone or screenshot
–> send it to this website -> https://postimages.org/Paste the link to the image here.
Infact as Plan B , you can use PostImages.ORG to upload pictures and select “Hotlink for forums:” , the links will look like this:
[ url=https://post images.org/][ img ]https://i.postimg.cc/G37B2wZD/rt125-test-image.jpg [ /img ][/url ]Just copy and paste and it will turn to this instantly when posting:
Sorry , I edited my reply to say this:
A bit too high 14.9 when idling – Should be 14.0-14.4v – but we can tolerate 14.5-14.6 as normal too.
Hyosung’s limit is 15V so you’re just on the border!
but OEM or Knockoff regulators are just wild = they would jump around from 11.5 to 16V! = 16V is basically time to blow up the battery or cook everything that’s attached to the harness that needs a 12v source.
Check yours again at 5,000 rpm (as per service manual) and tell us ?
I just seen your new reply now, i would check at 5k rpm and advise ?
Find out if voltage changes at the battery side when turning on the lights on/off , since these are 55 watts right out of the gate.
Since you have a brand new stator , the stator unit should be OK otherwise the bike wouldn’t start =A bike won’t start if its the wrong stator due to different pulse timing dots on the flywheel.
Also when the bike is running ===> disconnect the regulator , and disconnect only the “yellow” stator plug.
Measure at 5,000 rpm at the stator itself
Pin 1 – Pin 2 = Volts AC
Pin 1 – Pin 3 = Volts AC
Pin 3 – Pin 2 = Volt ACThis way we can check each yellow wire how much voltage in AC is being output at 5,000 rpm so we can fully rule out a new stator.
Then we progress further in to the harness itself if there is something on the harness or some kind of part attached to the harness that’s causing things to go haywire.
As long as the stator is feeding AC power in to the regulator itself ==> Disconnect the regulator from the harness and measure its 2PIN plug in DC , this should be between 14-15V DC , 13.5V DC would be Hyosung’s absolute acceptable lowest charging rate (less AC power when idling ofcourse)
Keep the yellow plug connected to the regulator , we’re just measuring the regulator’s 2Pin DC output once it takes the stators AC energy from the yellow wires.
I hope i made sense ? If not , let me know!
My bike loves to charge at 14.2V despite having the same kit as you , but it does the job, i would love to have 14.5V , but alas , its 14.2V all day , in any revs and has been that way for a few years now so i’ve yet to change the stator , it’s not bothering anyone. When i turn the lights OFF (removed the bulb!), then i see a big spike at 14.7V and stays there all day long.
So personally myself i have an achingly long job over the winter to strip the entire bike down to get to its harness and repair it and give it some nice TLC with ACF50 around its plugs , as to be fair some connectors near the front of the bike have oxidized a little bit (stupid wintry northern freezing wet climate! – I envy Australians)
Believe it or not , in July 2025 , i could not start the bike as the battery was 11V as soon as the key turned on (headlight is permanent ON for later models of the GT series bikes) , and i went under the bike , the headlight wires where burning my hands! – If i disconnect the bulb , she starts flawlessly , but connected them when running made the issue worse, i was flabber gasted – I tested the battery with a YUASA Load Meter (it does a deeper dive to verify battery is OK or not) , it was fine, mind you this was a YUASA battery which brand i trust the most and it was 3yrs old without fail , i swapped regulators again, same issue.
So in the end i replaced the bulb and got a new battery too. As the bulb was killing the battery other than the charging system. I wasted £120 all because of a bulb! – Mind you, this was 6 month old bulb too , so i made sure to get another one that isn’t “defective” / “bad batch” , excuse the quotes. I went back to my old regulator that’s always been good to me, and we are back to 14.2V (not a great number but ugh… old harness needs love eventually) and new battery , starts everytime now.
So i will make a routine to touch my headlight wires every now and then , and i also put a volt meter mod above the dashboard , that’s how i know the voltage is whenever i am with the bike. Great mod. Just tap in to your “side little bulb” inside your headlight and don’t cut the wires. Just copy the plug , make a “male – female” bridge
in the end [side light little bulb]–>female end–> (start of male mini bridge) with wires going to the volt meter–>female end of mini bridge) –> male end of the main bike harness. That way i can disconnect it at will and stays inside the headlight shell away from any water / nature attacks. Knowing Hyosung isnt making any harnesses for GT bikes (discontinued model) , best to preserve it.
I am digressing sorry , hope you had some ideas of checking for unusual power robbing along the harness too.
Do you have a short somewhere ? Ie parts of the harness touching the frame or…… 2 plugs are both 2 pin. One is for stator sensor One is for reg to harness Its easy to mix those two up & the harness gets fried or reversed terminals on the battery. 14.5V is usually the norm but 15V is Hyosungs limit as per manual. Disconnect your lights and see if bulbs affected them? I replaced my 4yr old bulb 3 days ago as the resistance grew so much the wires got too hot! Happy to test your reg again if you want to be extra sure as i did promise warranties provided the bike doesnt cook either the stator or reg & a new AGM battery is used (no lithiums) Confirm stator makes 65v-85v at 5k revs on each yellow wire via AC (service manual pn forum has tutorial) with reg unplugged?
just a follow up question, those 14.5 to 15 volts, are they at 5k rpm or idling? Because mine showed 14.9 when it was idling
A bit too high 14.9 when idling – Should be 14.0-14.4v – but we can tolerate 14.5-14.6 as normal too.
Hyosung’s limit is 15V so you’re just on the border!
but OEM or Knockoff regulators are just wild = they would jump around from 11.5 to 16V! = 16V is basically time to blow up the battery or cook everything that’s attached to the harness that needs a 12v source.
Check yours again at 5,000 rpm (as per service manual) and tell us ?
Congratulations!
This should be a fun off-roader!Start by getting the bike first , have a good look all around. Take some pictures on the day of delivery , post them on this forum so we can see what we’re working with.
Also be ready to give the engine a much needed checkup , they will last long if you take care of them 🙂 – I don’t know where to start until we find out what’s happened to the engine first ? So you may drain oil , remove the stator + clutch covers , see if there is anything suspicious ?
Ie. fried stator , damaged clutch plates , oil pump issue ? etc – Just wild guesses here. Hopefully should be a quick rebuild if it spins & starts well.
Did your harness have a BIG or SMALL connector for the Stator (Stator unit) ? or post a picture.
Can you try to upload an image directly on this forum?
If there is an issue with this site , please take a picture and upload it to the POSTIMG.CC website so i can see the errors preventing you using our image uploader.
The reason for asking is to verify if you have a Delphi V1 or V2 harness. So showing us the stator plugs and harness plugs will help me confirm what you have.
You said 2016 GT250R at the start of the post, so you may have 2016-2020 electronics but Hyosung can still use 2014-2015 electronics in other models made in 2016
(eg. 2019 bike at the dealership still has 2014 electronics inside it etc…)
Two Ports ECU = Delphi ECU. This requires a harness with 2-plugs for the Delphi ECU
Delphi Electronics have also changed, so to be safe get parts for 2014+ onwards
2008 – 2012 = Daewoo & Sentec ECU = Not made anymore and very very very difficult to find and fix!
So i would advise to upgrade all electrics to 2014+ model including harness , and you will find these parts on EBAY USA (It’s a big 250cc market)
Coils ?
HT Caps?
Stator Unit?These 3 need each other. If any of them are out of spec , there lies the “cut outs” you’re experiencing if it is electrical.
Try to get access to a cheap pocket meter and follow this topic:
Confirm back here your findings with the hard figures.
While the bike is apart, clean every single connector plug you can find with Contact Cleaner, incase some gold pins have oxidized due to nature , and ONLY (i mean only) use Dielectric Grease called ACF50 , it is #1 to have in every biker’s tool box. Don’t use anything like WD40 as it’s flameable. Just use ACF50 , after cleaning the pins , this helps the connectors maintain a good connection and not oxidize too soon.
Check for sparks again but this time , see if one coil is better than the other or replace the battery (if too old, the cells discharge too quick, you won’t have a good CCA left for it) , if battery is new , use a bike-charger (car chargers will burn the harness and the battery as there is too much current) , if jump starting = remove the battery out of the car and jump start , if the car / truck is running alive while you’re jump starting = you will quickly say goodbye to the GV250 (again, too much current).
Fortunately a GV250 carb is FARRRRRRR easier to get going than any GTR or GV Injected for that matter. I love working on those bikes when customers drop them off to me.
If they are IX plugs , they won’t be good for it. You want either the basic CR8E or LASER platinum plugs (but beware of fake NGK plugs now , it’s so bad there is even a post about it on NGK’s own website.)
If in doubt, get basic CR8E from halfords.After that, verify that both coils are actually sparking the same colour.
If not, go here below:
Rectifier – How to Test Stator , Battery , Regulator – GT125R Carby
Report back to this topic with readings of the stator, coils (without caps) and caps (on their own)
Ensure the airbox is fully secure, sometimes the front carb exposes some of its lip on the front airbox hole, so air leaks mean poor running, it is very very very picky when it comes to making sure the bike idles with a sealed air system.
Get carb cleaner , turn off choke, increase the idle ==> spray the engine rubber inlets. If the revs change for whatever reason, you may have cooked / caked up old o-rings, a fresh set would help restore its vacuum loss
Intake Pipe O-RING (Inlet Boot Seals) x2 – GV125 GT125 RX125 GV250 GT250 Hyosung
Whatever you do, make sure not to stress the rubber pipes as Hyosung isn’t making new ones anymore (they moved on to Gv125-S EFi now)
Double check the jet sizes and tell us ? eg. Front and Rear Pilots should be size 15 (forever) and rear mains should 87.5 & 90 as a baseline but can go up to 90 & 92.5 if you have an upgraded filter.
Like here:[Tutorial] How to swap Carb Main Jets – Hyosung GV & GT 125/250
if the bike has cone-filters , it will never run right until it gets its airbox. Hyosung made sure of it. everyone tried and failed, so airbox is a must. If the air filter is dirty, replace it as there is less air going in to the engine to mix the fuel properly , hence boggy running.
I may have said a lot , but take your time. 1 thing at a time. if you do a lot at once, you won’t know if its making progress or regressing (getting worse).
Wise but last war is crucially to check cylinder compression when it has warmed up but… let’s deal with that LAST.
The frame will twist and you will be in A&E before you have a chance to use the full power of the 650, there is a reason the 650 frames are built around the engine in trellis form and the steel is stronger than what Hyosung uses on the 250 frames. So personally i won’t entertain dropping a 650 in that frame to save your body.
Why not buy a spare engine and fit it yourself, it’s not too hard , just requires a lot of time and patience but your hands are free labour.
$1000 is cheap compared to UK standards as an engine alone in the UK is actually hovering around $500-800 USD with sketchy histories by last owners lol. Then couple dollars for labour ofcourse unless doing it alone.
